EP0715236B1

EP0715236B1 - Method of obtaining a temperature value for use in controlling the temperature of refrigerator

Info

Publication number: EP0715236B1
Application number: EP95308573A
Authority: EP
Inventors: Seong-Wook Jeong; Jae-in 707-908 Jugong Apt. Kim; Yung-seog 3-812 Samsung Apt. 333-3 Kang
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 1994-11-30
Filing date: 1995-11-29
Publication date: 2000-08-09
Anticipated expiration: 2015-11-29
Also published as: DE69518302T2; US5592827A; KR0165303B1; KR960018456A; EP0715236A1; JP2667137B2; DE69518302D1; TW314589B; JPH08226736A

Description

The present invention relates to methods of obtaining a temperature value for use in a temperature controlling method of a refrigerator and in particular, though not exclusively to such a method using a microprocessor, and more particularly, though not exclusively, to such a method which can optimally maintain a preset refrigeration temperature by precisely and quantitatively controlling the temperature.
Refrigerators are typically provided with plural thermostats, e.g., a freezer thermostat and a damper thermostat, for properly maintaining the inner temperature thereof. Here, the freezer thermostat is for automatically controlling the inner temperature of a freezer to which it is mounted, while the damper thermostat is for automatically controlling the inner temperature of a cold-storage compartment to which it is mounted. Such a refrigerator also has an evaporator and a bimetal thermostat for detecting a temperature increase of the evaporator when frost has been removed by a defrosting heater, and is mounted to the evaporator in order to stop the operation of the defrosting heater.
Figure 1 is a sectional side view showing the interior of a conventional refrigerator 10.
Referring to Figure 1, a freezer 11, a cold-storage compartment 12 and a crisper 13 are provided in refrigerator 10. Here, freezer 11 and crisper 13 are typically located in the uppermost and lowermost portions of the refrigerator, respectively, with the cold-storage compartment 12 occupying the midsection thereof. Each compartment has its own door lid, 12d and 13d, respectively. An evaporator 14 for absorbing heat from the inside of the refrigerator and thus cooling air inside the refrigerator while evaporating an influent liquid refrigerant at a low temperature is mounted to a wall (not shown) which separates freezer 11 and cold-storage compartment 12. A cooling fan 15 for circulating cool air by forcibly convecting the cool air is mounted behind evaporator 14. A freezer thermostat 16 for automatically controlling the temperature of freezer 11 is mounted inside freezer 11 and a damper-thermostat 17 for automatically controlling the temperature of cold-storage compartment 12 is mounted inside cold-storage compartment 12. A condenser 18 for cooling and condensing high-temperature and high-pressure gaseous refrigerant into a liquid state is mounted on the rear of the refrigerator. Mounted to the lower rear portion of the refrigerator, a compressor 19 is connected to condenser 18, to adiabatically compress low-temperature and low-pressure gaseous refrigerant into the high-temperature and high-pressure gaseous state. Reference numerals 20 denote foodstuff storage shelves.
In such a conventional refrigerator constructed as above, a microprocessor program is used to maintain three inside temperatures within different ranges (e.g., -12°C to -24°C for freezer 11, 0°C to 7°C for cold-storage compartment 12 and 5°C to 10°C for crisper 13). Each thermostat is electrically connected to a circuit board (not shown) on which the microprocessor is mounted.
In practice, however, the microprocessor can only recognize a temperature change of 0.4-0.5°C, at best. Therefore, in the case of food sensitive to a minute temperature change, i.e., less than 0.4°C, the food may degenerate due to a failure in temperature control.
It is an aim of preferred embodiments of the present invention to provide a temperature controlling method of a refrigerator using a microprocessor, which can optimally maintain a preset refrigeration temperature by precisely and quantitatively controlling the temperature.
According to the present invention, there is provided in a first aspect a method of obtaining a temperature value for use in controlling the temperature of a refrigerator characterised by comprising the steps of: sampling the inside temperature of the refrigerator a predetermined number of times to establish a sampled set of temperatures, establishing a sampled temperature value (X) occurring with the highest frequency within the sampled set; determining whether the frequency (X) of occurrence of the sampled temperature value (X) of highest frequency is not less than a predetermined frequency; when the frequency (X') of the sampled temperature value of highest frequency is not less than the predetermined frequency, and selecting the sampled temperature value as a controlling temperature.
According to the present invention in a second aspect, there is provided a method by using a microprocessor, further comprising the steps of: sampling digitized temperature values counted by an analog-to-digital converter according to a predetermined temperature range by a predetermined frequency by using the microprocessor; when the frequency (X') of the sampled temperature value (X) of highest frequency is less than the predetermined frequency, selecting a temperature value obtained by adding/subtracting a predetermined temperature value which is less than said predetermined temperature range to/from the temperature value (X) of highest frequency as the controlling temperature; and selecting a temperature value obtained by applying the steps to at least two temperature values (Y)(Z) with the second highest frequency and the third highest frequency, as the controlling temperature.
Suitably, said predetermined temperature range is 0.4°C and said predetermined temperature value is 0.1°C.
Suitably, when said temperature value (X) with the highest frequency is not less than 300 times and less than 400 times, if said temperature value (Y) with the second highest frequency is larger than X, a temperature value obtained by X-0.1°C is selected as the controlling temperature, and if Y ≤ X, X+0.1°C is selected as the controlling temperature.
Suitably, when said temperature value (X) with the highest frequency is less than 300 times and said temperature value (Y) with the second highest frequency is more than 200 times, if Y>X, X-0.1°C is selected as the controlling temperature, and if Y ≤ X, X+0.1°C is selected as the controlling temperature.
Suitably, when said temperature value (X) with the highest frequency is less than 300 times and said temperature value (Y) with the second highest frequency is not more than 200 times, if said temperature value (Z) with the third highest frequency is larger than X, X-0.2°C is selected as the controlling temperature, and if Z≤X, X+0.2°C is selected as the controlling temperature.
According to the temperature controlling method of the present invention, by way of example a quantitative sampling is carried out on the temperature value less than the temperature sensing resolution of a microprocessor. A controlling temperature value is then obtained from the sampled value and used for controlling the inner temperature of the refrigerator. Unlike the conventional method, the temperature controlling method of the present invention has an advantage that the inner temperature can be maintained optimally, i.e., such that a refrigerated commodity does not degenerate.
The present invention will become more apparent by describing in detail a preferred embodiment thereof, by way of example only, with reference to the attached drawings in which:
Figure 1 is a sectional side view showing the interior structure of a conventional refrigerator; and
Figure 2 is a flow chart for explaining a method according to the present invention, for controlling the temperature of a refrigerator using a microprocessor.
Referring to Figure 2, a temperature controlling method of a refrigerator using a microprocessor according to the present invention will be explained in detail.
In an analog-to-digital converter generally used in the refrigerator, actual temperature sensing resolution which can be recognized by a control unit (microprocessor) is about 0.4-0.5°C, when supply voltage (Vcc) is +5V with respect to ground. According to the temperature controlling method of the present invention, temperature change of 0.1 °C can be measured using a hysteresis loop between the microprocessor and a sensor.
First, digitized temperature values counted by the analog-to-digital converter per 0.4°C unit are sampled by using a microprocessor (step 21). Here, since the digitized temperature value is counted per 0.4°C unit, a temperature value out of the 0.4°C unit represents a larger or smaller value than the actual temperature. Then, it is confirmed whether the sampling has been performed at a predetermined frequency (or number for example, 500 times) with respect to the counted temperature values or not (step 22). If the sampling has been performed to the predetermined frequency, i.e., 500 times, a temperature value (referred to as X) counted with the highest (most) frequency, a temperature value (refer to as Y) counted with the second highest frequency and a temperature value (referred to as Z) counted with the third highest frequency are selected (step 23). Thereafter, it is confirmed whether the number (referred to as X') of the temperature X with the highest frequency is not less than a desired frequency (for example, 400 times) or not (step 24). If X' is not less than 400 times (X' ≥400), the temperature X is determined as a controlling temperature (step 25). If X' is less than 400 times, it is confirmed whether X' is in the range of not less than 300 times and less than 400 times (300≤X'<400) or not (step 26). When 300≤X'<400, if Y>X, a value obtained by X-0.1°C is determined as a controlling temperature, and if Y ≤X, a value obtained by X+0.1°C is determined as a controlling temperature (step 27). If X'<300, it is confirmed whether the number (referred to as Y') of the temperature Y is more than 200 times or not (step 28). When Y'>200, if Y>X, a value obtained by X-0.1°C is determined as a controlling temperature, and if Y≤X, a value obtained by X+0.1°C is determined as a controlling temperature (step 29). When Y'≤200, if Z>X, a value obtained by X-0.2°C is determined as a controlling temperature and if Z≤X, a value obtained by X+0.2°C is determined as a controlling temperature (step 30).
According to the temperature controlling method of the present invention, a quantitative sampling is carried out with respect to the temperature value less than the resolving power of a microprocessor. A controlling temperature value is then obtained from the sampled value and used for controlling the inner temperature of the refrigerator. Unlike the conventional method, the temperature controlling method of the present invention has an advantage that the inner temperature can be maintained in the optimal condition.

Claims

A method of obtaining a temperature value for use in controlling the temperature of a refrigerator characterised by comprising the steps of:

sampling (21) the inside temperature of the refrigerator a predetermined number of times, to establish a sampled set of temperatures;

establishing (23) a sampled temperature value (X) occurring with the highest frequency within the sampled set;

determining (24) whether the frequency (X') of occurrence of the sampled temperature value (X) of highest frequency is not less than a predetermined frequency; and

when the frequency (X') of the sampled temperature value of highest frequency is not less than the predetermined frequency selecting (25) the sampled temperature value as a controlling temperature.
A method according to claim 1, by using a microprocessor, further comprising the steps of:

sampling (21) digitized temperature values counted by an analog-to-digital converter according to a predetermined temperature range by a predetermined frequency by using the microprocessor;

when the frequency (X') of the sampled temperature value (X) of highest frequency is less than the predetermined frequency selecting (24-30) a temperature value obtained by adding/subtracting a predetermined temperature value which is less than said predetermined temperature range to/from the temperature value (X) of highest frequency as the controlling temperature; and

selecting (24-30) a temperature value obtained by applying said steps to at least two temperature values (Y)(Z) with the second highest frequency and the third highest frequency as the controlling temperature.
A method as claimed in claim 2, wherein said predetermined temperature range is 0.4°C and said predetermined temperature value is 0.1°C.
A method as claimed in claim 2 or claim 3, wherein, when said temperature value (X) with the highest frequency is not less than 300 times and less than 400 times, if said temperature value (Y) with the second highest frequency is larger than X, a temperature value obtained by X-0.1°C is selected (24) as the controlling temperature, and if Y≤X, X+0.1°C is selected (17) as the controlling temperature.
A temperature controlling method of a refrigerator by using a microprocessor as claimed in any one of claims 2-4, wherein, when said temperature value (X) with the highest frequency is less than 300 times and said temperature value (Y) with the second highest frequency is more than 200 times, if Y > X, X -0.1 °C is selected (29) as the controlling temperature, and if Y ≤X, X+0.1°C is selected as the controlling temperature.
A method as claimed in any one of claims 2-5, wherein, when said temperature value (X) with the highest frequency is less than 300 times and said temperature value (Y) with the second highest frequency is not more than 200 times, if said temperature value (Z) with the third highest frequency is larger than X, X-0.2°C is selected (30) as the controlling temperature, and if Z≤X, X+0.2°C is selected (30) as the controlling temperature.